cheribsdtest: Add test for canonical scalar function pointers

CTSRD-CHERI · Jan 26, 2025 · 0173154 · 0173154
1 parent eee9dfb
commit 0173154
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Showing 3 changed files with 33 additions and 0 deletions.
diff --git a/bin/cheribsdtest/cheribsdtest_fptr_canon.c b/bin/cheribsdtest/cheribsdtest_fptr_canon.c
@@ -30,6 +30,8 @@
  * SUCH DAMAGE.
  */
 
+#include <sys/types.h>
+
 #include <dlfcn.h>
 
 #include <cheribsdtest_dynamic.h>
@@ -82,3 +84,20 @@ CHERIBSDTEST(fptr_canon_dlfunc,
 
 	cheribsdtest_success();
 }
+
+CHERIBSDTEST(fptr_canon_scalar,
+    "Check that function pointers are canonical when cast to scalar")
+{
+	volatile ptraddr_t fptr_scalar;
+	void (* volatile fptr_dlsym)(void);
+
+	fptr_scalar = cheribsdtest_dynamic_dummy_func_scalar_address;
+	fptr_dlsym = (void (*)(void))dlsym(RTLD_DEFAULT,
+	    "cheribsdtest_dynamic_dummy_func_scalar_only");
+
+	CHERIBSDTEST_VERIFY2(fptr_scalar == (ptraddr_t)fptr_dlsym,
+	    "scalar %#p differs from dlsym %#p",
+	    (void *)(uintptr_t)fptr_scalar, fptr_dlsym);
+
+	cheribsdtest_success();
+}
diff --git a/lib/libcheribsdtest_dynamic/cheribsdtest_dynamic.h b/lib/libcheribsdtest_dynamic/cheribsdtest_dynamic.h
@@ -29,6 +29,9 @@
 void cheribsdtest_dynamic_dummy_func(void);
 void (*cheribsdtest_dynamic_get_dummy_fptr(void))(void);
 
+void cheribsdtest_dynamic_dummy_func_scalar_only(void);
+extern ptraddr_t cheribsdtest_dynamic_dummy_func_scalar_address;
+
 void * __capability cheribsdtest_dynamic_identity_cap(void * __capability cap);
 
 int cheribsdtest_dynamic_ifunc(void);

diff --git a/lib/libcheribsdtest_dynamic/cheribsdtest_dynamic_fptr.c b/lib/libcheribsdtest_dynamic/cheribsdtest_dynamic_fptr.c
@@ -44,3 +44,14 @@ void
 {
 	return (&cheribsdtest_dynamic_dummy_func);
 }
+
+/*
+ * This function must only be referenced as a scalar.
+ */
+void
+cheribsdtest_dynamic_dummy_func_scalar_only(void)
+{
+}
+
+ptraddr_t cheribsdtest_dynamic_dummy_func_scalar_address =
+    (ptraddr_t)&cheribsdtest_dynamic_dummy_func_scalar_only;